GWEN IFILL:And we close tonight with a look back as astronaut Neil Armstrong, the first man on the moon. He died on Saturday at the age of 82. NewsHour science correspondent Miles O'Brien has this remembrance.

MILES O'BRIEN (voice-over):It is undoubtedly the most famous footprint in history.

NEIL ARMSTRONG, astronaut:That's one small step for man, one giant leap for mankind.

MILES O'BRIEN (voice-over):Neil Armstrong was the first of 12 men to walk on the moon. He and crewmate Buzz Aldrin spent more than two hours on their historic walk and planted an American flag on the lunar surface. The date was July 20th, 1969, and an estimated one in six around the globe watched the landing unfold.

The crew returned to Earth and a hero's welcome, but Armstrong accepted the adulation reluctantly. Biographer James Hansen says that was partially because Armstrong felt many others deserved more credit than the astronauts were getting at the time.

JAMES HANSEN, author:He was always a fairly shy, introspective person. He didn't like the limelight much. And now finding himself in such a—in such bright lights, he withdrew even more. And then Neil just felt like, you know, all the attention on him was just out of place. And he wasn't really—it wasn't false modesty ever. It was just how he really felt about it.

MILES O'BRIEN (voice-over):Neil Armstrong was born in the small town of Wapakoneta, Ohio, in 1930. He became a Navy pilot after college, flying dozens of combat missions during the Korean War. Then he spent more than a decade as a test pilot, flying high-speed aircraft, including the X-15, which he flew at 4,000 miles an hour.

UNIDENTIFIED MALE:A new space team for the moon shoot.

MILES O'BRIEN (voice-over):In 1962, NASA made him an astronaut. During his first flight, Gemini 8, he successfully flew the first docking in space. But a system failure put the craft in a dizzying, dangerous roll. Armstrong managed to safely abort the mission, coolly saving the day, putting him at the top of the list for a moon shot command.

It was clear he had what Tom Wolfe later called "The Right Stuff."

JAMES HANSEN:NASA senior management knew that the first—the first man on the moon was going to be a global icon, was going to be world-famous and was going to be in all the history books forever. I mean, it - and it was the victory of the Americans in the space race. We never should forget that it was a competition.

And so the idea of Armstrong going out and having the kind of character that he did, senior management just felt that he would represent humankind and the United States in a very, very diplomatic and elegant way, distinguished way.

MILES O'BRIEN (voice-over):After his return to the moon to lasting fame, Armstrong seldom talked about the mission in public, as he did in 1989 with his Apollo 11 crewmates, Aldrin and Michael Collins.

NEIL ARMSTRONG:Apollo 11 was filled with vivid experiences. One that comes to mind, in my case, is the flying through the moon's shadow and seeing the sun eclipsed by the moon as we approached it. It was a very spectacular sight.

MILES O'BRIEN (voice-over):In 2009, the 40th anniversary, Armstrong recalled the role space exploration had on the Cold War, and the competition between the U.S. and the Soviet Union.

NEIL ARMSTRONG:I'll not assert it was a diversion which prevented a war. Nonetheless, it was a diversion. It was intense. It did a lot to both sides to take the high road, with the objectives of science and learning and exploration.

Eventually, it provided a mechanism for engendering cooperation between former adversaries. In that sense, among others, it was an exceptional national investment for both sides.

MILES O'BRIEN (voice-over):Remembrances have poured in since Armstrong's passing on Saturday. NASA administer Charles Bolden spoke today.

CHARLES BOLDEN, NASA administrator:In the words of the Armstrong family, the next time you walk outside on a clear night and see the moon smiling down at you, think of Neil Armstrong and give him a wink.

MILES O'BRIEN (voice-over):Over the weekend, tourists at the Air and Space Museum in Washington remembered where they were when Armstrong walked on the moon.

RICH HALDI, museum visitor:Barbara, my wife, asked me, "Do you remember what our son, Mark, when he was 2 years old in 1969, when we were watching it on TV, that Neil Armstrong was on the moon? And our son, who was 2 years old at the time, he went outside, looked at the moon and said, "We don't—I don't see anybody up there."

(LAUGHTER)

RICH HALDI:But—

BARBARA HALDI, museum visitor:We were sad to hear about it. He was certainly a pioneer and we all respected him in that day and age. I certainly wouldn't have gone up there and I don't know how they convinced him to do it.

JONNI OCEJO, museum visitor:Well, I was a 9-year-old kid, right? That was a big remembrance for us. We all sat around the TV and we all watched the whole process and it was a big deal. And it still is a big deal.

MILES O'BRIEN (voice-over):In Los Angeles, a wreath was set out at Armstrong's star on the Hollywood Walk of Fame, and people laid flowers at the foot of his statue at Purdue University, his alma mater. A private service is planned in Cincinnati on Friday.